They believe an attack on June 11 may be related to two others the next week, Holden said.

A woman was walking along 33rd Street near University Avenue in City Heights about 1 a.m. when a man knocked her down and tried to sexually assault her, Holden said. A passing vehicle scared him off, and he ran west on University.

Holden on Tuesday released a photograph of a man, taken from security video in the area, who may have seen something. He asked that anyone who can identify the man contact police at (619) 516-3000 or Crime Stoppers at (888) 580-8477.

In a similar case on June 17, a woman walking on Meade Avenue near 33rd, in Normal Heights was attacked by two men about 11:30 p.m. She fought them off. Police issued a composite sketch of one of the two men.

A sketch of a sexual assault suspect in Normal Heights. / San Diego Police Department

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A sketch of a sexual assault suspect in Normal Heights. / San Diego Police Department

The sketch is of as a light-skinned Latino, 23 or 24 years old, about 5 feet 8 inches tall. He was wearing a black shirt, a black and white checked long-sleeved shirt, and had braces. His companion was Latino, 28 to 29 years old, spoke with a Spanish accent and wore a hooded sweatshirt.

Then on June 21, two men knocked down a woman and tore at her clothes on Lincoln Avenue near Oregon Street in North Park about 9:40 p.m. Bystanders went to help her when she screamed, and the men ran.